Please help! Spotted this strange flying bird in silhouette last Summer, not sure but somewhere near Richmond in london, sorry not very precise! Size possibly: robin to dove size?
No interactions present.
Although you can't really tell from this photo, this is almost certainly going to be a pied wagtail. Grey wagtail would show an even longer tail and the photo shows none of the buff colouring you would expect on a yellow wagtail at this time of year. The tertials that Ophrys refers to are the feathers at the base of the wing, where it joins the body. They are short on most birds but noticeably long on wagtails and pipits. This bird's tail is too long to be a pipit.
Lat/Lng: 51.4492, -0.2955
OS grid ref: TQ185736